Devices for infusing to a patient a beneficial agent such as a drug diffused in a medical liquid are known in the art. The most common device utilizes an elevated glass or flexible container having a beneficial agent diffused in a medical liquid which is fed by gravity to a patient's venous system via a length of flexible plastic tubing and a catheter. The rate of flow in this type of device is commonly regulated by an adjustable clamp on the tubing. This set-up suffers from the drawback of requiring a relatively stationary patient and is dependent on the height differential between the medical liquid and the patient for accurate delivery rates.
An additional type of infusion device utilizes electro-mechanical components and a pump to provide fluid propulsion of the medical liquid for infusion into the patient. Such electronically controlled infusion devices, however, suffer from several drawbacks, including the cost of such electrical components as well as the limit such electrical components and the necessary power source place on the size and thus portability of the device.
Another type of infusion device utilizes a pressurized source of liquid provided by means such as an elastomeric bladder, a biased plunger in a syringe-type barrel or the like to provide the infusion pressure. A typical such device includes housing containing the source of pressurized liquid, an inlet aperture to load the liquid under pressure into the device, and an outlet conduit to expel the liquid into the patient. The outlet conduit typically includes tubing secured to the housing and in fluid communication with the outlet, a flow regulator to regulate the flow of liquid, and a catheter or a connector to attach to a catheter for infusion into a patient.
While such devices perform ambulatory infusion satisfactorily, the disposability of the devices suffers as the complexity of manufacturing and costs of materials increases. Additionally, because such infusion devices are used for differing infusion rates, different flow restrictors are utilized for different purposes. The use of dedicated outlet conduits require the manufacture of an entire device for each such specific use.
What would thus be desirable would be a disposable infuser device which allows flexibility of infusion rates while maintaining a comparatively low manufacturing and materials cost factor. The present invention achieves these requirements.